Conventionally, air dynamic bearings, a fixed shaft of which is fixed at both ends thereof onto a case and the like, have been known (for example, Patent Documents 1 to 4).
However, a position of one end of the fixed shaft is defined while the other end of the fixed shaft has been fixed at a time of mounting the fixed shaft. Given this, if the position of the one end is largely misaligned from an attachment position for the one end provided at the case, problems of performance degradation and reduced lifetime of the fluid dynamic bearing may arise due to axial eccentricity of the fixed shaft caused by an excessive force applied to the fixed shaft.
Patent Document 1: Japanese Registered Patent No. 3084600
Patent Document 2: Japanese Registered Patent No. 2645773
Patent Document 3: Japanese Unexamined Utility Model Application Publication No. H01-90022
Patent Document 4: Japanese Unexamined Patent Application Publication No. S59-17019